Flu Shots: Not So Helpful for Kids?

Kids and Flu Shots continued...

The children lived in Rochester, N.Y., Nashville, Tenn., or Cincinnati.

After controlling for a number of factors, including county of residence, gender, insurance status, vaccination timing, and whether the children had chronic health conditions that made them more likely to get the flu, the researchers could not show that the vaccine was effective in preventing flu-related medical visits.

They point out that during the 2003-2004 flu season, 99% of circulating influenza strains in the three communities included in the study were due to influenza A virus, but only 11% of the influenza A specimens across the U.S. were similar to a strain included in that year's vaccine.

The next flu season was milder, and Szilagyi and colleague point out that the vaccine was a better match. But, even so, only 36% of circulating virus was similar to vaccine strains.

"The lack of demonstrable vaccine effectiveness in our study may have been due to the sub-optimal match," the researchers write.

But they add that there is also evidence that adults vaccinated during the 2004-2005 flu season did derive some protection.

"It is possible that the vaccine has less effectiveness among children," they write.

Vaccination Still Important

Schaffner says the study was well designed and rigorously carried out. But he worries that the message some will take from the finding is that vaccinating children against the flu is a waste of time.

"Some parents and even some pediatricians are going to ask if vaccinating young children is really worthwhile," he says. "My answer is: 'Absolutely yes.' It is important to point out that more times than not over the last 20 years we have had a very close match between the vaccine and circulating strains."

He points to research suggesting that only about 30% of eligible children get flu shots, and only about half to two-thirds of those vaccinated for the first time get the necessary booster shot.

"Adults have more exposure to real influenza and past vaccines than children, so it makes sense that children might not be as protected," he says.